The amination of monoethanolamine with ammonia in the presence of a hydrogenation catalyst to produce ethylenediamine is well known and is commercially practiced. These processes generally produce other products such as aminoethylethanolamine, diethylenetriamine, piperazine, and aminoethylpiperazine. A general background on the production of ethylenediamine for monoethanolamine is provided by M. Arne, "Alkyl Amines", Process Economics Progress Report No. 138, SRI International, dated March, 1981, see particularly the section entitled "Ethyleneamines from Monoethanolamines".
A troublesome problem with the amination of monoethanolamine to make ethylenediamine has been the coproduction of significant amounts of by-products, particularly cyclic amines, especially piperazine and aminoethylpiperazine, that are of less commercial value than ethylenediamine.
Not only are piperazine and other cyclics formed, but such formation consumes the desired ethylenediamine. To avoid the formation of cyclic amines, the usual approach has been to reduce the overall ethylenediamine yields. For example, U.S. Pat. No. 3,068,290, states at column 4, lines 27 to 36;
"The condensation products [e.g., piperazine] are essentially formed at the expense of the ethylenediamine itself so that, as the transformation of monoethanolamine is going on, the transformation of the condensation products reverses and the ethylenediamine output decreases. The simplest method for limiting the ethylenediamine concentration, thereby the formation of its condensation products, consists in limiting the transformation of the monoethanolamine, the unchanged product being used then as a diluent." PA0 "Where selectivity is of primary concern in the amination process, it is preferred not to run the process to a high conversion. It has been found that selectivity to the preferred aminoalkanes decreases as conversion increases." PA0 "Generally, between about 5 and 20 percent of the converted ethanolamine may be obtained as diethylenetriamine, depending on the particular conditions that may be involved." PA0 " . . . the amount of piperazine yield may be reduced almost to the vanishing point, if it is undesirable for any reason to obtain such a product at the expense of higher ethylenediamine yields, by utilizing lower temperatures, greater quantities of ammonia and lesser relative amounts of the catalyst or shorter catalyst contact times." PA0 "Conditions favoring greater conversions to piperazine also tend to minimize the production of higher amine products."
U.S. Pat. No. 4,111,840, states at column 10, line 40 to 44:
The potential to aminate ethanolamine to produce diethylenetriamine in addition to ethylenediamine and piperazine is well known. For instance, U.S. Pat. No. 2,861,995 asserts at column 2, lines 13 to 16, that
The patent further states at column 2, lines 7 to 13, that
Again, the approch is one of reducing ethylenediamine yields to avoid piperazine production. The patent provides three examples which are summarized in the following table. In each example, the amount of Raney nickel catalyst used was 3.1 pounds. The ethanolamine conversion for the first run set forth in the table was reported to be 75 percent. The conversion for the other runs was not provided. However, the patent relates at column 1, lines 50 to 55 that conversions of 70 to 80 percent are readily achieved.
__________________________________________________________________________ Ethanol- Ethanol- Products as % of amine amine Temper- Converted Ethanolamine Feed Rate to Ammonia ature Pressure, Ethylene- Diethylene- lbs./hr. Mole Ratio .degree.C. psig diamine Piperazine triamine __________________________________________________________________________ 2.2 1:3.5 195 1950 24.1 29.8 14.52 1.6 1:3.3 160-170 1950 50.5 12.5 9.3 2.64 1:5.6 165 1500 60.8 about nil 16.34 __________________________________________________________________________
The patent also states at column 3, lines 20 to 22, that
Examples 1 to 5 of U.S. Pat. No. 3,151,115 employ a nickel-copper-chromium catalyst under differing process conditions for the conversion of monoethanolamine and ammonia to various amination products. The examples illustrated different temperatures for ammonia and monoethanolamine feed rates, and the effect of the addition of water. With process conditions favoring the formation of linear amines, considerable amounts of aminoethylethanolamine were reported to be produced. The examples can be summarized as follows:
______________________________________ Example 1 2 3 4.sup.1 5.sup.1 ______________________________________ Reactor temp., .degree.C. 199 198 198 223 227 Hydrogen rate; SCFH 800 800 800 800 800 Reaction press., psig. 2,800 2,800 2,800 2,800 2,800 Feed rates, gal./hr.: NH.sub.3 (anhydrous) 94 70 47 80 80 Monoethanolamine (MEA) 35.5 25.5 16 158 158 NH.sub.3 /MEA mol. ratio 5.6 5.8 6.2 1.1 1.1 Space velocity, 6.2 4.5 3.0 3.1 3.1 g/hr, ml. cat. Conversion of MEA, % 29.3 39.8 53.8 71.4 75.4 Yields (molar), %: Ethylenediamine 41.3 38.5 36.2 12.0 15.0 Piperazine 13.7 18.7 23.2 47.6 58.0 Diethylenetriamine 7.1 7.6 9.3 9.0 3.3 N--Aminoethylpiperazine 2.1 3.0 3.0 15.0 17.5 Aminoethylethanolamine 22.3 18.4 13.2 -- -- Hydroxyethylpiperazine 0.5 2.2 3.2 6.0 3.5 Residue 12.0 11.6 11.9 10.4 2.7 ______________________________________ .sup.1 Also used 140 gal. water/hr. in feed.
Russian Pat. No. 545,633 discloses a process for the amination of monoethanolamine using a nickel on chromium oxide catalyst to produce various polyamines. Examples 1 to 4 of that patent can be summarized as follows. In Examples 1, 2 and 4, the catalyst contained 50% nickel and 32% chromium oxide and in Example 3, 44% nickel and 51% chromium oxide.
______________________________________ Example 1 2 3 4 ______________________________________ Amount of Catalyst, cm.sup.3 100 50 50 50 H.sub.2 pressure, atm 160 120 160 160 Temperature, .degree.C. 200 170 200 200 Monoethanolamine 70 35 23 23 feedrate, cm.sup.3 /hr Monoethanolamine 60.7 40.0 80 32 conversion, % Products, % based on reacted monoethanolamine Ethylenediamine 52.2 60.6 46.0 88.0 Piperazine 25.8 16.0 37.9 12.0 Substituted piperazine 13.9 7.4 7.0 -- Aminoethylethanolamine 5.5 11.2 -- -- Diethylenetriamine 2.6 2.7 5.2 -- ______________________________________
As can be seen from these examples, conditions that favor diethylenetriamine production favor the formation of piperazine and disfavor the production of ethylenediamine.
East German Pat. No. 149,509 relates to a method for making polyethylene polyamines from ethylene oxide and ammonia without isolating or separating intermediate products. The product from the ethylene oxide and ammonium reaction is directly fed to an amination reaction zone containing hydrogenation catalyst at 150.degree. to 210.degree. C. The total process is stated to be conducted in a single up-flow reactor vessel. The pressure is maintained sufficiently high that a liquid phase is maintained in all reaction zones. The authors state that the amount of hydrogenation catalyst is selected based on the desired polyamine with liquid hourly space velocities of about 0.5 to 3 based on liquid product. Since the reaction is conducted in a single vessel, ethylene oxide can be expected to be present during the amination and relatively large amounts of oxygen-containing products such as diethanolamine, thiethanolamine, and aminoethylethanolamine, and it can also be expected that relatively small amounts of ethylenediamine will be present. This expectation is bourne out by the examples which are summarized below.
______________________________________ Example Component (mole %) 1 2 3 ______________________________________ Monoethanolamine 34.6 15.8 24.6 Diethanolamine 10.8 12.1 10.3 Triethanolamine 1.5 3.2 2.8 Ethylenediamine 11.9 8.3 9.4 Diethylenetriamine 15.2 21.6 20.8 Aminoethylethanolamine 12.1 9.6 14.0 Piperazine 7.8 10.2 6.8 ______________________________________
Diethylenetriamine is a well-recognized starting material for the formation of piperazine. See, for example, U.S. Pat. Nos. 2,267,686 and 2,809,195. In U.S. Pat. No. 2,901,482, a continuous process for making piperazine from diethylenetriamine is disclosed. The patentees note that the gas hourly space velocity for producing piperazine using a fixed bed of, e.g., Raney nickel catalyst is about 1 to 3 reciprocal hours.
N-aminoethylethanolamine is also a product that can be produced by the amination of monoethanolamine in the presence of ammonia. It is recognized that this product can readily form piperazine. For example, in Japanese Patent Application Kokai No. 49/11712, a copper and chromium-containing catalyst is disclosed for making piperazine from aminoethylethanolamine with high yields and selectivities.
When linear polyethylene polyamines are the desired product with the minimization of the production of cyclic amines such as piperazine, other types of processes such as the amination of ethylene dichloride have been employed. Another type of process is disclosed in U.S. Pat. No. 3,714,259. The patent describes a process for making linear polyethylene polyamines by reacting an ethyleneamine with an ethanolamine under certain process conditions including the essential absence of ammonia. The process is described as catalytic using a hydrogenation catalyst and is conducted under conditions such that the reactants are maintained in the liquid phase. See also U.S. patent application Ser. No. 454,485, filed Dec. 29, 1982, of Frank G. Cowherd III, herein incorporated by reference, which discloses the reaction of ethylenediamine with or without monoethanolamine under certain process conditions including conversions of less than about 35 percent to produce diethylenetriamine and minimize the formation of piperazine.
Although numerous processes have been disclosed for making ethylenediamine and/or piperazine by the amination of monoethanolamine, the production of diethylenetriamine by this route has generally been incidental. Little flexibility has existed in providing an amination product mix that maximizes diethylenetriamine production without undue sacrifice in ethylenediamine production while minimizing the production of cyclic amines such as piperazine and oxygen-containing amines such as aminoethylethanolamine. Indeed, the emphasis of many prior workers in the field has been to minimize piperazine formation by reducing the conversion of monoethanolamine to amine products. Such process directions have clear disadvantageous economic and processing features.